Wastewater occurs whenever a foreign substance is added to water that is not considered to add positive value to the water. The water is the carrier for these undesirable components, such as silt, dirt, ionic species, chemicals and sanitary fecal material. The water can be re-purified, removing the contaminants by mechanical, chemical or biological means.
Sanitary wastewater as it enters a biological treatment plant contains 1.5%-2.0% of suspended solids that are mostly consumed by bacteria in the reaction vessel. The remaining solids, or sludge is carried off and disposed of. The wastewater suspended solids are often referred to as the Biological Oxygen Demand (BOD). This number is roughly 250-mg/liter for raw sanitary wastewater. A four member household can typically produce 550-750 liters per day of sanitary wastewater. In addition to the suspended solids (BOD), 125-150 mg/liter of total dissolved solids (TDS) are added. As an illustrative example, if water were to enter a household with 300 mg/liter of TDS, the same water will leave the household at 425-450 mg/liter TDS. Therefore, the water leaving the home is “carrying off” human waste, soap and other materials from the shower, laundry, kitchen, and other drainage pipes carrying household wastewater.
The wastewater from residential homes and other dwellings as well as restaurants, hotels, schools, and other commercial buildings finds its way to a wastewater or sewage treatment plant via forced (pumped) or gravity piping systems. This wastewater collection piping system is often referred to as a sewer main.
The wastewater treatment plant can be configured in numerous ways with strainers, settling basins, biological reactors and filters. The primary goal is to reduce the BOD to less than <5 in the treated wastewater. The water is then further treated and often used for irrigation, or returned to deep wells, rivers or other bodies of water.
Municipal wastewater treatment plants at the time of their construction are often designed for projected future urban growth. Years after their construction, they are often expanded, as required, to satisfy actual urban growth demand. Similarly, wastewater collection piping systems are designed to handle a given quantity of wastewater based on projected demand. For the purpose of this disclosure, the term “wastewater loading” is defined as a quantity of wastewater flowing through a sewer main per unit time. Also for the purpose of this disclosure, the term “solids loading” is defined as a quantity of solids (i.e. matter with specific gravity greater than one) contained in the wastewater in a sewer main.
In growing cities and suburbs, many of the wastewater collection piping systems are overloaded or will be overloaded in the future with not enough capacity to handle the demand for wastewater flow. Those skilled in the art have devised several ways to remedy this situation. One solution is to lay parallel pipes or replace the current pipes with larger pipes to accommodate the additional wastewater loading. Another solution is to build additional waste treatment facilities to handle the additional loading. Both solutions can be expensive to implement. In addition, replacing or adding new pipe can be disruptive to a large portion of the neighborhoods and roads where the new pipes are being laid.
For the forgoing reasons, there is a need for a method, system or apparatus that can adjust the wastewater loading in a wastewater collection system in order to increase the system capacity.